Fontenelle‘s tale of the golden tooth, originally from his 1687 Histoire des Oracles (English with some formatting issues here) but quoted here (in italics) as found in Paul Hazard’s Crisis of the European Mind 1680-1715 (La Crise de la conscience europeen) and book-ended with Hazard’s (non-italics) commentary:

Everybody knows about the story of the Gold Tooth, a diverting tale, well conceived and full of significance. Let us read it once more, for its lesson never grows stale, and as we read let us recall the sensation it made when it first came out. Fontenelle, while seemingly indulging in a little harmless amusement, touches in reality on three matters of profound human concern: Science, History, and Religion.

In the year 1593, the report got about that, somewhere in Silesia, a child of seven had lost all its teeth, but that one of the missing.molars had been replaced by another, all of gold. In 1595, one, Horstius, Professor of Medicine at the University of Helmstad, wrote an account of this tooth, giving it as his opinion that it was partly natural, partly miraculous, declaring that God had bestowed it on the child in order to console the Christians for the sufferings they had undergone at the hands of the Turks. Truly, a strange sort of consolation! And of what possible concern could this tooth have been to the Christians, or the Turks? That same year, so that the Golden Tooth should not be lacking in historians, Rullandus wrote another account of it. Two years later, Ingolsteterus, another man of learning, wrote a work in which he contested Rullandus’ views on the Golden Tooth, whereupon Rullandus came out with an elaborate and erudite rejoinder. Yet another eminent person, named Libavius, collected and collated all the statements that had been put forward in regard to the tooth, to which he appended a theory of his own. These works were all very impressive; only one thing was lacking and that was any clear evidence that the tooth was a gold one at all. On its being handed to a goldsmith for examination, he discovered that a piece of gold leaf had with amazing dexterity been superimposed on the tooth. First came the books about it; afterwards, the expert examination by the goldsmith.

That is what happens in all manner of cases. It is just human nature. What in my view brings home the extent of our ignorance is not so much the facts which really are facts, but which we cannot explain, as the explanations we produce of the facts which are not facts at all; which is as much as to say that while we have no principles that should lead us to the truth, we have plenty of others well calculated to lead us away from it.

Learned men of science clearly demonstrated how it was that underground places were warm in winter and cool in summer; then other scientists still more learned, came along with the discovery that the whole thing was a mistake and that the original statement was entirely incorrect; underground places were not warm in winter and cool in summer.

Historical questions are still more liable to this sort of error. We discuss and argue about what the historians have told us. But these historians—what manner of men were they? Had they not their own passionate predilections? Were they not credulous, or ill-informed, or inaccurate? Find me a single one who examined his subject, whatever it may have been, with a completely unprejudiced and attentive eye.

All this is especially pertinent when your particular subject-matter happens to be concerned with religion. In such cases, according to the side you are on, it is no easy matter to avoid ascribing to a false religion virtues which it cannot claim, or to a true one, virtues which it does not need. However, we ought clearly to understand that, just as we can never add truth to what is true already, so we can never impart truth to what is intrinsically false.

At first, he seems to be indulging in a little playful banter; but gradually, as he proceeds, his tone becomes graver and graver. Through all these airs and graces, the underlying idea, profound though it be, is clear enough and it obviously tallies with what Bayle had said in the matter of comets; the likeness is unmistakable. There is the same appeal to a wider audience than that of the professional philosophers and theologians, the same pitiless denunciation, first, of human frailty, the primary cause of all error, next of tradition, which blindly takes error to its bosom, fortifies it and renders it all but invincible. Some absurd idea or other crops up; the Ancients take it seriously and give it their imprimatur; then we, the later generations, accept it with our eyes shut, on the authority of the Ancients. The process never varies. Get half a dozen people to believe that the sun is not the source of daylight, and the thing is done. In time, whole nations will come to believe it.